A glamorous Syrian woman who used to be married to a middle eastern military intermediary has emerged as the mystery investor who has bought a 2 per cent stake in Cordiant, the advertising group.

Nahed Ojjeh lives in Paris, loves chess and is regularly described as a "multi-millionaire" or even "billionaire".

She is the widow of Akram Ojjeh, the Saudi billionaire who has been described as "one of the region's most efficient military intermediaries".

Mrs Ojjeh is the daughter of general Mustafa Tlass, the Syrian defence minister. She was also an associate of Roland Dumas, a former French foreign minister. Mrs Ojjeh's interest in Cordiant is a mystery to the company and WPP, the advertising giant which is pursuing a £266m bid for the company. Mrs Ojjeh's office in Paris could cast no light on the trades, saying she was on holiday.

According to a stock exchange filing, which emerged late on Wednesday evening, Mrs Ojjeh spent £116,000 on buying more than four million shares at an average price of 2.85p, well above WPP's 2.4p offer price.

Quite why she has done this is unclear. WPP has already declared its £266m offer final, meaning it cannot be increased. And if rebel shareholder Active Value blocks the deal, Sir Martin Sorrell's WPP has said Cordiant will fall into administration.

Active Value has increased its stake in Cordiant to 27 per cent, giving it the power to block the WPP bid if it chooses. If Mrs Ojjeh is acting in concert with Active Value it would take the grouping close to the 29.9 per cent shareholding which would oblige them to bid for all the remaining shares. However, Active Value denied this yesterday: "She has no connection to Active Value," said a spokeswoman for the fund management group.

Mrs Ojjeh is best known for her attempt to take chess to the masses via a new world championship. She teamed up with a UK media company, Einstein Group, to launch the tournament. But the two fell out and Einstein applied to the courts to be placed in administration yesterday. Mrs Ojjeh took over a traditional Paris Chess club in March 2002. She later organised a chess "super-tournament" called the NAO Masters in Cannes and set her sights on other big projects in Europe, Asia and the United States.

Asked about her motivation, she once said: "I have often asked myself why chess is so neglected in education. Chess enables the young mind to have an insight into the fights and quarrels of family life.